1. Field of the Invention
The present invention relates to a strap-band type connecting device which has a strap band to wind around a connecting portion between a tubular element and a metallic pipe with a predetermined winding force, and particularly concerns to a strap-band type connecting device which is improved to insure a sufficient strength at a cross piece segment formed between neighboring slits, with which a rod screw brings its helical thread into tight engagement upon rotationally operating the rod screw.
2. Description of Related Art
A strap-band type connecting device has a strap band provided to wind around a connector hose which serves as an article to be wound. In recent years, the connector hose has been used to vehicular air-conditioners which compress liquid refrigerant with high pressure. The connector hose also has been used to vehicular turbo-chargers which are exposed to a high pressure with a high ambient temperature. To cope with those adverse environments in which the connector hose is installed, high endurance properties have been required for the connector hose.
In order to increase a mechanical strength of the connector hose, the connector hose is reinforced with a hardness-increased rubber or shored up with an increased number of fibers embedded in the rubber.
As an alternative, the strap band is integrally formed with the connector hose by means of a synthetic resin so as to produce a glue-compound structure. The connector hose formed by the glue-compound structure requires a winding force higher than the ordinary rubber hose had needed. Various ways have been searched for seeking how to insure a stable winding force at the connector hose.
As a general structure of this type of strap band, an array of slit teeth is provided at one end side of the strap band, and a housing is provided at the other end side of the strap band.
Within the housing, the one end side overlaps with the other end side of the strap band, a rod screw engages its helical thread with the slit teeth, and makes the one end side slide against the other end side of the strap band so as to tightly wind around the connector hose in combination with a rotational operation of the rod screw.
As examples of the strap-band type connecting device, prior art references in turn introduce a screw band (Laid-open Japanese Utility Application No. 07-44962 referred to as a first reference), a hose clamping device (Laid-open Japanese Utility Application No. 01-176293 referred to as a second reference), a hose clamp (Laid-open Japanese Patent Application No. 2003-28366 referred to as a third reference), a hose clip (Laid-open Japanese Domestic Patent Application No. 06-507465 referred to as a fourth reference) and a clamping device for connection (Japanese Patent No. 4738328 referred to as a fifth reference).
In the first through fourth references, the rod screw engages its helical thread tightly with respective bridged braces appeared between the neighboring slit teeth in combination with the rotational operation of the rod screw. Especially when a higher torque is applied to the rod screw, the bridged braces would be subjected to a larger amount of bending force from the helical thread, and unfavorably deforms to lose the winding force so as to resultantly lax the strap band.
In the fifth reference, the strap band is wavily deformed across a width direction to form a wavily curved area where a series of slit teeth is situated. This increases an engagement area between the bridged brace and the helical thread of the rod screw, so that the bridged brace could resist against a larger bending force, to which the bridged brace is subjected from the helical thread upon rotationally operating the rod screw.
However, especially when a higher torque is applied to the rod screw, there arises a possibility that the strap band tightly presses the wavily curved area on the other end side of the strap band so as to plastically flatten when the wavily curved area slides on the other end side of the strap band, due to the reason that the one end side overlaps with the other end side of the strap band. This apparently results in the rod screw deteriorating the engagement force against the bridged brace to accidentally lax the strap band.
Therefore, the present invention has been made with the above drawbacks in mind, it is a main object of the invention to provide a strap-band type connecting device which is capable of impart an increased geometrical moment of inertia to a cross piece segment against a circumferential direction of a strap band, thereby insuring a rigidity higher enough to resist a bending deformation force, to which the cross piece segment is subjected from the rod screw upon rotationally operating the rod screw, and resultantly reinforcing a bridged brace to sufficiently resist an engagement force with an improved durability.